For all the intense promise and awesome potential of the upcoming Porsche 918 Spyder, the very first running prototype looks a mess as it hoves silently into sight across the Nardo test track in southern Italy.

The squat two-seater, with two extravagant top-exiting tailpipes pointing skywards out of the engine bay at the rear, could be mistaken for a home-built project rather than a multi-million-pound precursor to what’s likely to be the world’s most advanced supercar.

This is the only 918 Spyder prototype in existence, clothed in a mix of modified 911 panels and, it seems, anything else laying around the workshop floor. It’s a rolling chassis to test the petrol-electric hybrid drive components to see if they operate reliably in the tight confines of the new car.

Once Porsche is satisfied the engine, motors, battery and other electronic units achieve reliability standards, it will begin to construct more production-ready prototypes. Most are earmarked for durability testing, but some will end their lives against an offset barrier as part of crash testing.

Four-square stance

The initial impression of the 918 Spyder is its ultra-low height. It looks tiny, but it quickly becomes clear it follows the trend of other recent wide, high-end supercars. At 4643mm long, 1940mm wide and just 1167mm high, the 918 Spyder is 30mm longer, 19mm wider and the same height as the Porsche Carrera GT. It rides on the same 2730mm wheelbase but, even at this early stage, it is clear the production car will have a four-square stance.

Inside the two-seat cabin, wiring runs everywhere and getting in isn’t easy. There’s a wide carbonfibre sill, wires and other electric devices littering the cabin. The 911 GT3 seat and six-point harness, is positioned just 270mm above the ground – the same as for the production car. It is lower than the Carrera GT, which boasted one of the lowest seats in the business.

Once settled, I can take in the low dashboard, 911 steering wheel, Boxster instrument binnacle, wide centre console, stubby gearlever, extreme windscreen and limited rearward vision. The cabin is pretty improvised at this stage and created to ensure the prototype is driveable. This prototype has a fixed roof, but production models will have a removable roof panel.

First sensation? Torque, and lots of it. It weighs nearly 1700kg – 400kg more than the car it replaces – but the 918 bolts out of the blocks with all the abandon of the Carrera GT, if not quite the same aural intensity.

Le Mans-derived V8

The mid-mounted 4.6-litre V8 – related to the 3.4-litre unit from Porsche’s LMP2 racer – and two electric motors serve up 762bhp and 552lb ft in total. The 918 Spyder is the most powerful road-going car Porsche ever. The reserves are channelled through a combination of direct drive (on the front axle) and seven-speed, dual-clutch gearbox (on the rear axle) to either the rear wheels or all four wheels together.

According to Porsche’s simulations, the 918 Spyder will cover 0-62mph in 2.8sec, 0-124mph in 8.9sec and 0-186mph in 26.7sec. Porsche claims it will return 94mpg on the current European cycle – in pure electric mode.

The car pulls away silently. As speed builds, the two electric motors whirr and there’s a ping of stones flicked into the carbonfibre wheel houses. Traction feels incredible from a standing start, but it is the relentless acceleration that grabs my attention.

Before the end of the straight, the 918 Spyder’s naturally aspirated engine kicks into life with a suppressed roar. Those signature pipes, which will be shorter and more styled on the production car, exit behind the rollover hoops less than an arm’s length away.

The engine has been tuned to rev to more than 9200rpm in production trim, so it should possess the razor-sharp throttle response of the Carrera GT. The prototype has a conservative redline of 7000rpm, in the interests of reliability. The expectant shrill at higher revs is currently replaced by a slightly disappointing baritone woofle, although it won’t be long before Porsche puts that right.

Towards the end of the straight, Bartels lifts off the throttle and puts big weight behind the carbon-ceramic brakes – grabbed by eight and six-piston calipers. Despite huge retardation, it doesn’t bother the ABS.

Efficient KERS

There’s a good reason for such abrupt braking. With a hi-tech recuperation system used to collect kinetic energy, Porsche claims it is three times more efficient than regular systems. Hammering the stoppers keeps the lithium-ion battery charged. The electric range is put at 16 miles, limited to 93mph, but at the speeds we’ve just hit the charge is quickly drained.

With a turn and a whiff of oversteer, we head back. The firm ride copes with expansion joints without being overly harsh. Unlike the Carrera GT, which featured pushrod-operated springs and dampers attached to the monocoque, the 918 Spyder has a more conventional arrangement. We slalom through a row of cones with next to no body roll. With a low height and all the heavy components mounted below the car’s centre line, I’d expected that.

The front end also grips resolutely. The agility is hugely impressive, inviting and exciting in equal measures. We can only wonder what it’ll be like with a full aerodynamic package. The rear spoiler, not evident on this prototype offers varying levels of downforce - more than 200kg at the claimed top speed of 202mph.

My ride in the first-ever 918 Spyder comes to an all-too-early end. As we discuss the car’s potential and my admiration for Porsche’s engineering efforts, the stop-start cuts in to preserve fuel levels. Once again, there’s silence, interspersed with the odd ‘tick’ of heat dissipation.

It may not look like much at the moment, but this Porsche is shaping up to be a talented and useable all-rounder. Right now, 18 September 2013 is appearing like a landmark day, not only for Porsche but also for the history of the supercar. Mark it in your diary.

Join the debate

OK, so it does 94mpg for 16 miles on pure electric. What does it do over a more sensible distance when it's running on a combination of petrol and whatever it can harvest from braking? (My car does 70mpg+ coasting downhill, so all I need to do is drive to the top of Pikes Peak and coast down and I've got myself the most fuel-efficient V8 in the World....not!)

[quote Autocar]For all the intense promise and awesome potential of the upcoming Porsche 918 Spyder, the very first running prototype looks a mess as it hoves silently into sight across the Nardo test track in southern Italy.

The squat two-seater, with two extravagant top-exiting tailpipes pointing skywards out of the engine bay at the rear, could be mistaken for a home-built project rather than a multi-million-pound precursor to what’s likely to be... Read the full article[/quote] Having just read the article it does sound like cake and eat it stuff, but, i can't get my head round the 94mpg,how is this calculated?